Before the Civil War: The Newtowncunningham incident in Co. Donegal, May 1922

On the 4th May 1922, a convoy of pro-Treaty IRA men drove through the town of Newtowncunningham, Co. Donegal, and came under fire from a party of their anti-Treaty counterparts. The engagement lasted no more than three minutes, yet had been savage in its intensity, with three men killed, all Donegal natives from the pro-Treaty side. One survivor described it as a "veritable tornado."

That it was an ambush, as initially reported, would be among the details disputed in the days to come.

(Pro-Treaty soldiers on a lorry)

At the inquest conducted by the pro-Treaty authorities, it was claimed that the convoy had been callously lured into a trap. In response, Seán Lehane, the commanding officer of the anti-Treaty IRA in Donegal, wrote to the press to tell his side of the story.

His men in Newtowncunningham, he said, had been unaware of the identity of the convoy coming towards them, thinking it to be of the British military that was stationed in nearby Derry. When the newcomers were revealed to be fellow Irishmen, Lehane called on them to halt and had instead been fired upon. In the resulting shoot-out, it had been the Pro-Treatyites, Lehane claimed, who had precipitated it with the first shot.

Lehane also stressed the essentially defensive nature of his side: "On several occasions parties of them were at our mercy, but we fired only with the intention of dislodging them."

It was only later that the news that a truce between the two hostile factions had been signed in Dublin that morning reached Donegal - too late to have made a difference in Newtowncunningham.

One detail that Lehane left out was that he had been in Donegal, despite being from Cork, in the first place as part of a joint venture, secretly agreed by Michael Collins and Liam Lynch, to continue the fight against British rule in Ulster. The Anti-Treatyites would provide the manpower, while the other side supplied weapons.

At some point, however, this accord had gone badly wrong, resulting in five deaths altogether on the 4th May, two of them civilians, and a furthering of the bitter divisions between former comrades.